Sorry it was slower than you wanted, but I think the uphill (even if slight) and the hairpin turn were probably both factors slowing you down.  Hopefully your other mile courses coming up will be a bit easier.  Still, it's a good starting place, and it should make it easier to train for and strategize for your other mile event(s) this season.  And a 5:29 is still pretty darn fast, all things considered!  Especially considering that is with no mile-specific training.  Great job!