The character are holding hands (重ねられた左手) and the narrator complains this is the second time he gets 「上等だよ」 today.
そわそわ感を滲ませつつも by itself (leaving つつも aside) it's akin to "an uneasy feeling is made spread".
What I'm not quite sure is the use of 感触に.
Does it spread into the 感触に or does it spread because of 感触に?
I understand 感触に can be used for the cause of something for example (for example あまりの寒さに目を覚ました) however I'm not sure if it's the case with 感触 here.
Does it spread into the touch or does it spread /because/ of the touch?