trans temp and engine temp getting really high than droping while idli

[jesse1]

hi I have 2011 Silverado 4.8l trans temp is getting up to 93 Celsius while idling and engine temp gets to about 112 Celsius than drop back down to 90 and 100 than climbs again only while idling I have 75000 km on it so not much I always keep an eye on trans temp and it usually only around 40-50 Celsius and engine temp has never gone past 100 before on me so just wonder what it could be before it gets worse or if this is normal for these trucks