Yea. Next time just thank her for her support that day and leave it at that. Smile and look into her eyes when you say it. Be very upbeat about it. But make the thank you quick and give her 100% attention when you say it. I believe that this is how you truely feel. The coming together and stand-offish should not matter. What should truely matter is that she was still there. Read no more nor less into it. Take a gift when it is freely given and give thanks for that gift.
And if you do not feel up to it. Switch weekends. Again another thoughtful gift. Hell, if I switched weekends I would center the conversation around getting some comfort food from her for the switch. I would say it in a joking manor and smile, maybe even laugh. If she brings some comfort food then take it as a thoughtful gift again. And thank her. If she does not get take out....
Flowers always make people better, happier, and more helpful; they are sunshine, food and medicine for the soul. unconditional love is awesome!