It depends what makes those keys work well for you, Bob. Do some of the melodies stick within half an octave? Are you content to have the occasional low note come out a bit breathy or rumbley instead of cleanly? If you can comfortably and pleasingly sing the same song in both E and B, yes probably a bit unusual for an untrained, un-warmed-up voice.

I wouldn't be surprised if, upon analysis, the lower keys have a doh-to-doh melody and higher ones sol-to-sol melody, or vice versa depending on your vocal range. Maybe you have two octaves of very comfy range rather than the more common 1.5 octaves. Another reason for more flexibility in keys is a voice with no break so you needn't concern yourself with avoiding it.