Not sure where you're from but in my dialect (North American) it's more common than not to have _have_ realized as [əv] ("uhv") in contexts like _should have_, _could have_ (but not _I have a car_, where it has to be the full [hæv]). Only in deliberately enunciated speech do I feel like I'd expect [hæv] in the former kind of context. So it's an understandable mistake to make.