Worn oil seals on the valves

Went to look at a 2004 Honda 450 and when he fired it up it smoked like crazy.I mean BAD!!! The bottom had been done about 2 years prior.The head wasn't done.My question is, could the seals be bad enough that when the bike sits for a week could enough oil run down on top of the piston to make it smoke that bad for about twenty minutes or so or might there be something else.I didn't do a compression test but we had to use the pull start to get it going and it seamed to have a lot of compression.Not sure if it was because of all of the oil sitting on top of the piston or not.The bike only has 3340 km on it and seems to be in good condition other than that.Any thoughts?