samtools apparently resets the COLUMNS variable to 110 every time I run it. Which version are you using? I tried both 1.3.1 and 1.6, and it's the same.
$ COLUMNS=1000
[statgenpro ~/WORK/DCM/For Carol]
$ echo $COLUMNS
1000
[statgenpro ~/WORK/DCM/For Carol]
$ $samtoolsdir/samtools tview -p chr14:23898059 -d T $dir/$samp.sorted.dedup.realign.recal.bam | sed -n '3p'
CCACTGCCTTCCCATGTCTGGTCCACAGCTGGCTCTAAGCAAATAGCTGTTGAATGTGGGAGCGAGTGAGTGATTGTTCT
[statgenpro ~/WORK/DCM/For Carol]
$ echo $COLUMNS
110