The problem with your script was a indentation problem, that is common with python beginners:

python script.py 

  File "script.py", line 28

    print p.sprintf("Authentication Request from [%Dot11.addr1%] to AP [%Dot11.addr2%]")



                                                                                   ^

IndentationError: unindent does not match any outer indentation level

the space between ]") and ^ is filled with tabulation characters and that confuses the interpreter. Here is with the indentation corrected:

#!/usr/bin/env python



######################################################

#   authWatch.py v. 0.1 (Quick, Dirty and Loud) - by TinMan

#   Place card in monitor mode and set the channel. 

#   If you want channel hopping, run airodump-ng in 

#   another terminal. Will add channel hopping 

#   in the next version. 

######################################################  

#

#   Usage: python authWatch.py 

#   



import sys

from scapy import *



interface = sys.argv[1]



def sniffReq(p):

     if p.haslayer(Dot11Deauth):

# Look for a deauth packet and print the AP BSSID, Client BSSID and the reason for the deauth.

          print p.sprintf("Deauth Found from AP [%Dot11.addr2%] Client [%Dot11.addr1%], Reason [%Dot11Deauth.reason%]")

# Look for an association request packet and print the Station BSSID, Client BSSID, AP info.

     if p.haslayer(Dot11AssoReq):

          print p.sprintf("Association request from Station [%Dot11.addr1%], Client [%Dot11.addr2%], AP [%Dot11Elt.info%]")

# Look for an authentication packet and print the Client and AP BSSID

     if p.haslayer(Dot11Auth):

            print p.sprintf("Authentication Request from [%Dot11.addr1%] to AP [%Dot11.addr2%]")

            print p.sprintf("------------------------------------------------------------------------------------------")

sniff(iface=interface,prn=sniffReq)