Riften got tore up, and I haven't even been to riften until now.
Doubtful. It's far more likely that your first visit to Riften just happened to coincide with a vampire attack that you weren't even aware was happening at the time you arrived. This is especially likely in Riften given that you're expressly told that you need to enter from the front gate (alternatively, you can enter through the meadery, but given the circumstances I'll assume for now that you came in by way of the front gate).
Vampires, when they spawn into Riften, will do so from the opposite side of town. So, if you came in through the front gate and stopped to chat with Maul, or Shadr, or Mjoll (as players will often do upon entering Riften for the first time), you may have not realized a vampire vs townies/guards altercation was in progress at the time of your arrival.