After perusing SuperUser I came over here to Meta and checked my profile. I noticed I had mysteriously gained +5 reputation putting me up to
106. This is strange because I haven't asked any questions nor posted any answers here yet, is this a bug?
Your reputation for the meta site is drawn from your main Super User profile. It is cached and updated on the hour.
Any change in reputation you see here in the grey zone already happened in the world of colour back on the main side. It just takes a bit to catch up. Question upvotes are scored at +5 and will be the cause of that particular bump in reputation.
This slightly laggy mirror on reputation is the same behaviour across the other sites in the Stack Exchange network.
Except for Meta Stack Overflow which is the Stack Exchange nation's capital and works with its own reputation bucket.