Ultimately, unless you get the landlord to alter the 'no pets' statement, they can evict you anytime they feel like it. It's a ready-made excuse for them, regardless of what they told you verbally. It's a fairly simple change, have your landlord put a line through the no pets sentence and write 'snake OK' in the side margin and initial it. Then be sure you have a copy of that lease somewhere safe. As long as you go in to meet the landlord and be confident, you shouldn't have any issues. Be firm and don't go for the whole 'we can work that out later' after you sign the lease shtick. It is well worth the peace of mind.

My .02

~Kat