Thats actually pretty decent.
Its not 100% indicative of not having a problem though. Pings come across port 80, port 80 is never blocked unless you want to just totally dick over the internet.
When you talk to Tech support at Comcast, ask them to check the ports that Bungie mentions in their port forwarding guide. Hell, if you are lucky you will get someone that plays Destiny on the phone (This happened to me with WoW and CoD when I had issues with Mediacom)
They will most likely blame the problem on your end, but regardless, they should send someone out to look at your lines, especially if you are in an Apartment. Tell them you want a new Modem, not router, most Comcast modems are Scientific Atlantic, or Motorola, models from 2002. They are seriously out of date. When I was in Chicago, I bought my own and was able to get better than advertised bandwidth at the time.