It means, take it as it goes... lol.. no pun intended.
Seriously though, take your relationship as it goes. Don't overanalyze something (such as he suddenly went offline suddenly and was gone for 12 hours and didn't say goodbye to u), don't label anything (are we like,.. truly madly deep lovers?) etc.. it just means, have fun and take it easy.
Don't jump into things you guys aren't ready.