Now it's foremost on his mind.
After throwing ball one to Denard Span with two outs, Lee walked off the mound and tapped his left arm with his glove hand.
''It's pretty much the same thing as it was before,'' said Lee, who said he felt some discomfort throwing before the game and for the first few warm-up pitches each inning.
''The last inning, it never fully went away and it came on a little stronger the next six or seven pitches I threw,'' he said. ''It was there every throw and I just felt like if I kept throwing something was going to snap and I just wanted to make sure that didn't happen.''
Lee, making his third start since missing two months, left the game with an apparent recurrence of the flexor pronator strain that sidelined him in May.
The 35-year-old will be examined by the Phillies team doctor Saturday.
''I mean it was all but gone,'' Lee said of the injury. ''It was out of my mind, and I wasn't thinking about it at all until today when I was throwing those pitches, and there it is again.''
Grady Sizemore had three hits and three RBIs as the Phillies pounded out 17 hits.
Antonio Bastardo (5-4) relieved Lee and retired Span, the only batter he faced, and got the win.
Span had two hits and two RBIs.
Gio Gonzalez (6-7) failed to make it through four innings for the second time in three starts. He allowed five runs and eight hits over 3 2-3 innings.
''A lot of pitches right in the middle of the zone,'' catcher Wilson Ramos said. ''That was a problem today. A lot of pitches up in the zone, too.''
With Ryan Zimmerman sidelined, the NL East-leading Nationals bolstered their infield Thursday, acquiring two-time All-Star Asdrubal Cabrera and cash from the Cleveland Indians for shortstop Zach Walters.
Cabrera will play second base with Anthony Rendon shifted to third in Zimmerman's absence
It was Revere's fourth straight multi-hit game.
''Ben's just really peppering the ball, squaring up and using the whole field,'' Phillies manager Ryne Sandberg said.
The Nationals pulled within 5-3 on Span's 2-run single in the fifth.
Philadelphia added two in the sixth on Rollins' RBI-single and Utley's sacrifice fly.
Nationals: Manager Matt Williams said there's still no timetable for the return of Zimmerman, out since July 23 with a strained right hamstring.
''He's going to do nothing for two weeks,'' Williams said. ''We'll make an evaluation after that.''
Nationals: Doug Fister (10-2, 2.69) will be looking to win his sixth straight decision when he faces Philadelphia on Friday. He's 5-0 in his last six starts, with a 2.21 ERA.
Phillies: Roberto Hernandez (5-8, 4.14) looks to continue his recent success. Over his last three starts, he's 2-0 with a 2.61 ERA.
Nationals: For Cabrera, the Nationals parted with Walters, 24, who hit .234 with three homers runs and six RBIs in 40 games over the last two seasons.
''By shock, as anybody else would,'' Williams said about how Walters's reacted to the news. ''He got called into the office, he thought he was in trouble for something, and I said 'No, we've made this trade.'''
Phillies: Despite much speculation, the deadline passed without general manager Ruben Amaro making a move.
''We were looking for players that would help us,'' he said. ''But I think we were very reasonable in the discussions that we had. Frankly I don't think the clubs were aggressive enough for the kind of talent that we have on our club.''