The simple answer would be too much oil. Did you recently do a "cold" oil change? If so... if that is your only symptom and your motor runs fine (i.e., its getting oil), I would get it up to running temp, then do another oil change. If you need to drain a little oil out, do it through the filler neck. I've used a bulb-type hand syphon to do it in the past. You can pick one up at the auto parts store for @ $3 and they come in handy for other applications such as syphoning fuel out of your tank when you need to replace your crossover line.
2006 Softail Night Train
K&N in / V&H out