Is it good that I left my coworkers suddenly and went skate at lunchtime?

Not at all. We all need some space.

ssmoothies no I would not say your are weird at all some days you can of had enough of the pressures of work and your co workers so you just need to get away for a bit to wind down and chill that's what I do we have a rest room where I work for breaks and mealtimes so at lunchtime I go down to our canteen with my bait box and a mug of tea have my dinner and read the papers just space on my own to chill from the morning activity

No you are not

I worried because I've once been told I have to be in the groups in workplace by someone I worked with... I think it might somehow important but I really couldn't do it

Nope, some time to yourself is always good.

Stop being so worried about what is "weird" or not.