Found this answer in an eth forum. Fyi for the next noob.
Pools, and blockchain explorers too, are not reporting the hash rate that you see on your system from the miner's output. They are reporting a hash rate based on the rate at which you are mining blocks with a given difficulty. In other words, if you mined X blocks in 1 minute with a difficulty of Y, they can calculate your effective hash rate. They don't know the hash rate your miner is reporting locally, which is calculated based on the number of hashes your GPU kernel ran during a timed interval. Since, the pools use the block mining rate to calculate an effective hash rate, that rate varies considerably, because there's a variance, due to statistical probabilities, in when and how often you actually mine a block (or part of a block in the case of pools). What you are seeing is perfectly normal on a pool hash rate report.