To me there's an uncanny-valley effect. Maybe it's the Looneys or the kilometres on the road signs, but it definitely feels the tiniest bit different.
On the other hand, the difference between a dialect and a language is an army and a navy, neither of which Canada has much of.
Midland American English is what we would call the standard American accent. Most of Iowa, South Dakota, Nebraska, Kansas, Missouri, Illinois, Indiana, Ohio, and parts of surrounding states speak in this.