Hello Richard,

     If it would make you more comfortable about the tree location , then move it. Gas lines are usually located about 18 to 24 inches below the soil surface.  The roots won't damage the line but future work on the gas line could damage the tree. I am including a few links below for you to review in reference to tree planting and location. The proximity to overhead power lines and building structures would be a greater concern as the tree grows  taller and wider. 

     If you replant the Maple be careful of the planting depth and of the location of the root flare. That is the portion of the tree just above the soil level. 

     Small shrubs of your choice should not be any problem planted in this location as it is not directly over the gas line. 

chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://csfs.colostate.edu/wp-content/uploads/2022/06/How_to_Properly_Plant_a_Tree_CSFS-v1.pdf

https://www.srs.fs.usda.gov/pubs/misc/ag_654/volume_2/acer/rubrum.htm

https://hort.ifas.ufl.edu/woody/root-growth-depth4.shtml

chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://wayne.osu.edu/sites/wayne/files/imce/Tree%20planting%20for%20the%20home%20landscape%20Gary%20Graham%20April%2030%20article.pdf