Forgot piece on fermentation lock

I have had my batch in the fermentor for about a week. I noticed early that I didn't see much action, but I was trying to be patient. As it reached a week, I now noticed I forgot the inner piece to my fermentation lock, possibly allowing air to get into my beer. I quickly found the piece and put in on, but I'm not sure if it's too late. Any ideas, should I pitch more yeast and introduce it? Should I just let it go and deal with it? Please help.
Thanks Dave

I wouldn't worry, especially if you had the little cap on the top. During the first week there's plenty of CO2 creating positive pressure to keep any nasties out.

Leave it be. Some folks just put tinfoil over their primaries. Other folks even leave them open, though I wouldn't recommend it.

The layer of CO2 over your beer will have protected it from oxidation. You have a slightly higher risk of contamination, but the odds are still well in the favor of good beer.

ok, great. thanks for your replys. I, of course, was going to drink it either way, but it puts my mind at ease.

Yeah don't worry about it. I usually let mine open ferment with a paper towel over it for 2-3 days during high krausen.