Split Up and Reconnected

My partner and I were together for six years before we got divorced last month. Since then, I've been trying to move on but found myself reconnecting with him in unexpected ways. We've had a few casual dates and one night, things went further than just dinner. It felt like an old habit coming back to haunt me. Is it normal to slip so easily into past dynamics? Should I push away these feelings or try to find some middle ground?