My GF and I both got some spawns outta eggs such as Kabuto and Geodudes. Our suspicion is that they changed eggs so that any eggs hatched during the event are subject to "event spawns" not predestined spawns. Just a theory we had discussed although too early to say.
The reason why? Cuz they want to make money not have spoofers and free players hold eggs till double candy(more likely they half distances). 2nd they want to reward players who walk AND use 9 incubators.
I am happy for you and your luck with hatching. It points out a critical point witch needs to be addressed, the unfairness and bad balance in the game. My last 15 10km where 12 (12!!!) Mantines, 2 gligars and one Sudowoodo. I feel the opposite of reward for running 9 inc. and for being a legit player. Why not even it out 4 everybody in every biome???
Rural trainer, lv 35 pissed off