City Water In Filling Fresh Water Tank

I put the pump back on city water three days ago and have not had any instances of water flowing back into the fw tank. But since I had already ordered the anti siphon valve, I decided to install it. I cutoff all water to the pump, turned on the pump, and opened a faucet to relieve all pressure in the lines. Then I installed a Shurflo anti-siphon in-line on the outflow side of the pump. I put air into the accumulator (approx 26psi) and turned water back on. Eveything's good, except. About every 7-10 seconds the pump takes what I would describe as a "bump". It's like it is receiving a jolt of electricity, not long enough for the pump to engage, and then it cycles off. The whole process is no more than a second in duration. I left the pump on this afternoon and this same cycle continued. Not sure if it is air in the line or what. I plan on running on the pump for a couple of days and see what happens. Just curious if anyone has any other ideas.