My megamim I think it was at the time or whatever it was, never learned petal dance. It tried to learn sweet sent twice. Why did it do that??
It is also possible that you evolved your bayleef at a later level than 32. In other words your bayleef was level 31, you battled someone, and you gained 2 levels. Just have it relearn the move later down the road.
If you evolved Bayleef at level 33 and want Petal Dance try to get a heart scale if you don't already have one by using Rock Smash on yeah, rocks and go to Blackthorn City where the move remember is in Heart Gold and soul silver.
in Diamond Pearl and Platinum the move remember is in Canalave City and in sinnoh you can get a heart scale undergound.