I have to assume they said it correctly by accident or unintentionally

Well, maybe it's a regionally variation, as Faldo suggested earlier in the thread. If you hear it all the time, it's probably well under way to becoming standard (for the region). Just out of curiosity, where do you live? And do you hear rs being dropped elsewhere?

This reminds me of the brouhaha over AAVE aks pronunciation of ask. The fact, that as far back as Old English, both pronunciations have been in free variation, is usually unknown by those complaining.

Ceci n'est pas un seing.