On what exchange was it filled (from your execution reports)?
IB, at one time, had a prohibition against opening an odd-lot position in NYSE/AMEX stocks. I'm guessing that, instead of rejecting the orders, they now send them to ARCA or INET, where there was someone offering $1 above the AMEX offer.
What doesn't make sense to me, though, is that I don't think a market order is supposed to route to an ECN, or if it does, it's supposed to be simulated as a limit order that is a small amount through the NBBO (i.e. not $1). It would be good if you would ask IB to clarify what happened here (and tell us).
You do realize that, by buying 1 share, with a $1 minimum commission, you're already giving up 1.7%, regardless of fill quality? I'm assuming this is a retirement account of some kind, and you're regularly buying with new contributions. You'd really do better to buy more shares less often.