Getting a cracked iPhone screen repaired but not from apple?

The screen on my iPhone 4 cracked. I have Verizon so I went to a Verizon store to just use an upgrade and get a new phone but it was really complicated so I didn't do it. I called apple and they said it'll be 149. The guy I talked to said it'll void my warranty if I go anywhere else other than apple to get it replaced and they can tell if it's a different glass if I ever had an issue with it again and had to take it to apple. But I never even go to apple. If I have an issue with my phone (which is never, until now) I go to Verizon. But I don't even know if I have a warranty? I bought the phone from Verizon. And I don't have insurance on it

I got mine fixed for $50 at a Mexican place lol worth it