Originally posted by VehiX
I'd contribute this to temp changes in your area. Has it been getting cooler in the morning or when you happen to notice this?
Actually, it has been getting a bit cooler in the mornings... this morning was 48 degrees when leaving for work. It's been raining a bit as well.

Originally posted by VehiX
Could also indicate a spark plug issue.
Do you mean, like a bad seal around a spark plug?