If you asked Clark, he'd say that he'd reached out because he thought that Bruce might, possibly, wobble in the intensity of the sensation. That was entirely why he reached out with one hand and spread his palm against Bruce's abdomen as the other slid up his side, settled at the hip. That was definitely why the touch was reverent and needing and almost desperate and why he actually let out a gasp of relief as he finally got his hand on Bruce's skin. As soon as he can, he answers that almost smirk with a definite grin.