However, he made his return in Bordeaux last week and looked to be back to his old self as he ran in two tries against Mont-de-Marsan.
Speaking after the game, though, his first consideration was for the team performance.
"It was really important for us to put a marker down after the disappointment of the London Irish game.
"And to finish top of the group, with six wins from six, that makes it a good day.
"We were positive today. We set out to play with good width and sometimes our execution let us down a bit. But, we were a bit more clinical in the second half and finished a bit better and that's good.
"The quarter final is a long way off, and there's a lot of rugby to play before then, but it's great to have a big game on the horizon to look forward to."
In terms of his personal contribution, May is simply happy to take things slowly after his long absence.
"It's obviously a case of building my confidence, week on week. I'm starting to feel a lot more confident in my knee, which is only natural after a long spell out.
"I've missed out on quite a few games and that's always frustrating. So, it's good to be back and I'm pleased to have played my part these past two weeks."